Regenerative repeater



933. E. P. BANCROFT 1,931,099

REGENERATIYE REPEATER Filed Feb. 26, 1932 FIG. I

INVENTOR ERWIN F. BANCROFT BY g ATTORNEY Patented Get. 17, 1933 UNITEDSTATES REGENERATIVE REPEATER Erwin P. Bancroft, Brooklyn, N. Y.,assignor to International Communications Laboratories, Inc., Newark, N.J., a corporation of New York Application February 26, 1932. Serial No.595,305

I 6 Claims.

This invention relates to regenerative repeaters of the start-stop type,in which are used simple, inexpensive mechanisms that are easy to adjustand maintain. It is designed primarily for use with what are known asBaudot or equal element codes.

Start-stop regenerative repeaters heretofore proposed have consistedessentially of two start stop mechanisms, one used in connection withreceiving anddistributing incoming signals and one used inretransmitting them, together with intermediate elements for storing thesignals during the interval between the reception and theretransmission. The mechanisms have been complex, expensive and, in manycases, difiicult to maintain.

In start-stop systems, the code signals representing the characterstransmitted are usually preceded by a start impulse and followed by a gostop impulse. In such systems, the transmitter is arranged to stop in aposition corresponding to the stop impulse, while the receiver, since itis set in motion by the start impulse, isadjusted to stop in a positioncorresponding roughly to the g5 mid-portion of the start impulse. Thus,between the transmitter and the receiver there is a phase difierenceapproximately equal to one impulse of the code. This phase differencemay be increased somewhat by having the transmitter stop in a positioncorresponding to the beginning of the stop impulse and the receiverstart from a position corresponding approximately to the end of thestart impulse. In the repeater described herein, this phase differencebetween the receiving and transmitting distributors is utilized to setthe individual elements of the transmitter in positions forretransmitting the signal completely regenerated.

My invention is illustrated in the accompanying drawing, wherein:

Fig. 1 is a developed plan view of the single rotating element, showingthe receiving distributor and the receiving relay diagrammatically;

Fig. 2 is a view of the end of the unit of Fig. 1 on the line 2-2, andshows the relative positiohs of the single transmitting contact androtating element;

Fig. 3 is a view of the opposite end of the unit of Fig. 1 on the line33; and

Fig. 4lshows the start-stop clutch mechanism.

Referring now to Fig. 1, 8 is a hollow cylinder shown developed, inwhich slides 41 to 46 are mounted to slide parallel with the axis of thecylinder. At one end of each of these slides a pin is mounted. A groovedcam 11 is fixedly mounted on the frame (not shown) in such a positionthat as the cylinder rotates the pins 31 to 36 on the ends of slides 41to 46, respectively, will pass through the grooved portion 11 of the camand, at one instant, be centered between theirextreme rightand left-handpositions. Located Just past this centering point is a'knifeedged wedge10' carried by the armature 10 of a power relay 32. The wedge 10 isarranged to guide the slides 41 to 46 into either their left-' orright-hand positions in accordance with the positioning of armature 10.In case it is desired, the pin 36 may be omitted from slide 46 and thelatter permanently positioned in its right-hand position.

Located opposite one another at the end of the drum 8 are two cam levers12 and 13 which op-. erate in conjunction with slides 41 to 46. Theselevers are rigidly fastened to the contact arm 14 shown in Fig. 2. Thewhole assembly is pivoted at 31 and is biased to rotate in a clockwisedirection (Fig. 2) by a spring 30.v Contact arm 14 co-operates withfixed contacts 15 and 16. The arm 14 is connected to line L over whichthe" regenerated signals are set by the arm engaging contacts 15 or 16.The angular relation between the groove 11,' the switch 10', the levers12, 13 and contact arm 14 is such that the arm 14 is operated to theposition determined by the position of the slide, immediately followingthe positioning of the slide.

It will be noted that cam lever 12 is shorter than lever 13. In thesystem with which this repeater is particularly designed to operate, itis proposed to operate with an equal element code, for example, sevenequal units in case the fiveelement Baudot code is used. It isfurtherproposed to obtain the full length stop pulse by having the transmitterstop for at least a definite period at the conclusion of thetransmission of each code signal. It is, therefore, necessary, in such asystem, to have the .cam which co-operates with the slide which controlsthe stop pulse shorter. than the cam which co-operates with theremaining slides. Therefore, in this arrangement, cam lever 12 isconstructed to co-operate with slide 46 only while cam lever 13co-operates with the remaining slides. With such an arrangement, it ispossible to have the transmitting and receiving distributors operatingat the same speed and still transmit over the line an equal element codesignal. It is obvious, of course, that, if the stop impulse from thetransmitting station is made longer than the other impulses, cam lever12 can 110 I proposed to delay the start of the drum 8 by' be dispensedwith and all operations of the contact lever 14 controlled by cam lever13.

As has already been explained, slides 41 to 45, or '46, are disposed intheir rightor left-hand positions, as the cam drum 8 rotates, by meansof the wedge in controlled by the armature 10 of relay 32. Belay 32, inturn, is under control of the received signals- If now the slides arepositioned toward the left, as by a spacing signal, their right-handends will miss the cam surfaces 12 and 13 as they pass the latter, andthe contact arm'14' will be rotated by spring 30 to close contact 15.If, however, any of the slides arepositioned toward the right byamarking signal, their right-hand ends will pass beneath the cam 12 or13, causing them to rotate about pivot 31 to close contact 16. It willthus be seen that conr tact 15 or 16 will be closed in accordance withthe setting of the.- slides 41 to 46, which inturn is determined by theposition of the wedge 10' at the'time the pins on the ends of slides 41to 46 pass the wedge 10'.

v The drum 8 is mounted on a shaft 9 which is driven through aclutch-mechanism 18, shown in Fig. 4, from any suitable source of power,such as a constant speed electric motor. In order to increase the timeallowed for the setting of slides 41 to 46 by the received signals overline L, it is means of a delay mechanism shown in Fig. 4. In thisfigure, any standard clutch, such as shown in United States Patent No.17,725 of July 3, 1930, may be used.

Pawls 19 engage a stop pawl 20 to disengage the clutch mechanism fromthe driving shaft. The

. stop pawl 20 is held in a position to engage pawls 19 by means of aspring 21. The stop pawl 20 is arranged to be disengaged from clutchpawls 19 by means of a lever 23 normally held in the position shown bystop 29. Lever 23 is under constant tension of spring 24 and rotates ina clockwise direction about its pivot 25. Stop 29. is under control ofthe armature 10 of relay 32. The operation of this armature to thespacingposition (right-hand position of wedge 10', Fig. 1) willdisengage the stop 29 from lever 23, allowing the latter to operate anddisengage stop lever 20 from clutch pawls 19. As shown, there is aclearance between lever 23 and stop lever 20. Some time, therefore, willelapse, between the time lever 23 is released for operation and the timeat which stop lever 20 releases pawls 19,

.thereby allowing the clutch mechanism to engage. The amount of timerequired for this operation will be determined by the clearance betweenlever 23 and stop pawl 20, the weight of lever 23 and the tension ofspring 24. It is evident, therefore, that the interval betweenthereceipt of the start pulse and the time at which the shaft 9 starts torotate can be varied within certain limits by changing either the weightof lever 23 or. the tension of spring 24. Preferably, the arrangementshould be such that shaft 9 will start to rotate at a time correspondingapproximately to the beginning 'of the #1 selecting impulse, that is,the end of the start impulse. Lever 23 is returned to its normalposition ofrest by means of a cam 17 carried on shaft 9. Lever 23 andstop 29 are arranged so that when the latter releases the former, stop29 will be held clear of the armature 10 of relay 32 duringthe'signalling period and will come into position to be operated by thearmature 10 only duringv the stop interval.

It will be noted that the operation of this regenerative repeater isentirely mechanical and that it employs a single receiving magnet inseries with the first line and a single transmitting contact fortransmitting signals to the second line. No other electrical circuitsare required for the operation of the repeater except those which may berequired in. connection with the source of power used for: driving themechanism. If a,

two-way repeater is desired, I two elements, exactlylikethose-described, and driven from a com-. mon source of power, may beused.

' ,While I have shown my invention applied to a start-stop system, itmay be equally well applied to a synchronous system as the slides wouldbe equally spaced, one for each element of the code.

As in synchronous systems, aporrector mechanism would be added tomaintain the repeater in synchronism with the received impulses.

United States patents to York and Benjamin,

NOS. 1,191,933 of July 18, 1916, 1,215,605 of February 13, 1917, and1,298,622 of March 25, 1919, show corrector mechanisms as applied torotating commutators, which corrects by moving the brushes in properrelation to the commutators. Such a corrector mechanism may be appliedto my type repeater by having the corrector mechanism move the rotatingelement which carries the slides 41 to 46 to its proper position What isclaimed is: r 1. In a regenerative repeater, the combination ofa relayfor receiving signals, a rotatable device provided with a plurality ofslidesadjustable to I I one of two operating positions, means forpositioniiig said slides intermediate said operating positions,switching means associated with said receiving relay and placedimmediately subsequent to said slide positioning means with respect tothe rotation of said rotatable device to position said slides in oneofsaid operating positions, a set of transmitting contacts, and meansassociated with said slides to operate said contacts immediatelyfollowing the Ipositionmg of said slides.

2. In a regenerative repeater for operation with i 3. In astart-stopregenerativerepeater, arotary member carrying on its surface membersslidable in the direction of the axis of rotation, a receiving relay,means for starting a rotation of said rotatable member, means undercontrol of saidv receiving relay for initiating operationof saidstarting means, and means interposed between said relay controlled meansand starting means to delay the operation of said starting means.

4. In a start-stop regenerative repeater, the combination of-means forreceiving signals of two difi erent characters, a rotatable memberearryingmovable slides, means controlled by said signal receiving meansto cause a single rotation of said rotatable means, a positioning membersaid receiving means in accordance wi the character of each -signalthereby to control the positioning of said slides during said rotationaccording to the character of the received sig 14-5 moved to one or theother of two positions of,

nals, and a set of contacts operable by said slides to transmit signalssimilar in character to those received but of regenerated shape andduration.

,5. In a regenerative start-stop repeater, the combination of means forreceiving signals, a rotatable member carrying a plurality of slidesaxially positionable along said member, means for positioning saidslides in accordance with received signal impulses, a set oftransmitting contacts, means comprising bell crank levers operable bysaid slides as said rotatable member revolves for connecting saidtransmitting con- .tacts to line, one of said levers being positionedfor operation by one only of said slides, and the second lever beingpositioned for operation by the remaining ones of said slides.

6. In a regenerative device for repeating signals each of which iscomposed of a start element, signal elements and a stop element, arotatable member carrying slidable members on its surface, means toinitiate a rotation of said member a definite time after reception of astart impulse, means to move said slides to position corresponding tothe character of said signal elements a definite time after receptionthereof in order, a set of transmitting contacts, means comprising abell crank lever operable in accordance with the positioning of saidslides to transmit signals corresponding to said received signalelements in character but depending on the length of contact of saidslides and levers for their duration, and means comprising a bell cranklever to transmit a stop pulse from said contacts said pulse dependingboth upon the length of contactof said lever and one of said slides andupon the time intervals between the reception of a start pulse and theinitiation of rotation of said rotatable member for its duration, andmeans to stop said rotatable member after each revolution thereof.

ERWIN P. BANCROF'I.

